Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
#define INF 1e9
using namespace std;

char f[60][60];
int c[60][60];
int h,w;
int dy[4]={1,0,-1,0},dx[4]={0,1,0,-1};

bool contain(int y,int x){
    return (0<=y && y<h && 0<=x && x<w);
}
void dfs(int y,int x,int cost){
    if(!contain(y,x) || f[y][x]=='#')return ;
    if(c[y][x]>cost){
        c[y][x]=cost;
        for(int i=0;i<4;i++){
            dfs(y+dy[i],x+dx[i],cost+1);
        }
    }
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin>>h>>w;
    int ans=h*w;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            cin>>f[i][j];
            if(f[i][j]=='#')ans--;
            c[i][j]=INF;
        }
    }
    dfs(0,0,0);
    ans-=c[h-1][w-1]+1;
    if(c[h-1][w-1]==INF)ans=-1;
    cout<<ans<<endl;
}